Inquiry continues into 2009 HF release at Citgo refinery, CSB says

The US Chemical Safety Board (CSB) dispatched a team of investigators on Mar. 6 to the site of a July 19, 2009, hydrocarbon gas release involving hydrofluoric acid (HF) at Citgo Petroleum Corp.’s Corpus Christi, Tex., refinery. Citgo was able to capture the estimated 21 tons of HF that were released from the plant’s alkylation unit and subsequently satisfied recommendations CSB issued the following December, the board noted.

It is continuing its inquiry because of HF’s toxic nature and the need to keep it contained or to mitigate consequences of its release, CSB Chairman Rafael Moure-Eraso said. “Approximately 50 of the nation’s refineries still use HF in their alkylation units, requiring great care in its handling,” he indicated.

The released hydrocarbons in the 2009 incident ignited and became a fire that burned for several days and critically injured one employee, CSB said. Citgo reported to the Texas Commission on Environmental Quality that 21 tons of HF released from alkylation pipes and equipment were captured by a water mitigation system, the federal agency said.

But investigators quickly determined that Citgo nearly exhausted the stored supplies for the water mitigation during the first day, causing the 163,000-b/d refinery to begin pumping salt water as a backup, it added. Multiple failures occurred during the salt water transfer including ruptures of barge-to-shore transfer hoses and water pump engine failures, it said.

The board said its December 2009 urgent safety recommendations called on Citgo to immediately improve the plant’s water mitigation and perform third-party safety audits of its HF units there and at its Lemont, Ill., refinery. Citgo met the recommendations’ requirements and CSB closed them as acceptable actions in 2011, it said.